1. Field of the Invention
The present invention concerns methods and devices able to authorize the use of a program protected by an electronic cartridge. It is applicable more particularly to the renting of software or programs so as to be able to control the number of hours or a renting limit date. It could also be used for the renting of a machine, the program in question being in this instance the operating system of the machine.
2. Description of the Prior Art
Computer systems are increasingly used to operate devices. A large number of programs are available to the user to make the most of his equipment. These programs are used in a wide range of fields: management software, measuring software, etc. Generally, they are stored in memories integrated with the device. In the micro-computer field, these programs are stored in a magnetic memory known as a hard disk.
Problems of cost and fast obsolescence are urging industrialists to take these programs or renting software. Thus, programs are rented out to customers.
The renter then needs guarantees which provide against any possible abusive usage of his material by limiting renting to a certain number of hours of use or up to a certain date. This dissuades a dishonest customer from keeping the material longer than he ought to, copying the program onto another machine or even selling it.
To resolve these problems, various solutions have been put forward and a large number of systems have been studied. This is why an electronic cartridge system has appeared. The customer needs the cartridge to gain access to the software he rents. This cartridge is connected directly to the customer's computer system by means of a connector. The program can only function in the presence of this cartridge, because during its running, the program checks and periodically scans the presence of the cartridge and ensures that the period of validity is not used up or that the limit date of validity has not been surpassed. However, these systems are not highly adapted to the principle of renting. Firstly, at the end of the renting period, the software is no longer usable unless the cartridge is changed, which requires sending physical objects between the renter and his customer. Secondly, there are cartridges able to be reset by a smart card. In this case, the cartridge is basically a smart card reader (possibly with a standardized format). But this method also requires that the user send the smart card back to the renter to either change or reload it.